title: Long-lifetime Ru(II) complexes as labeling reagents for sulfhydryl groups.
abstract: We report the synthesis and spectral properties of two long-lifetime highly luminescent Ru(II) complexes containing either a sulfhydryl reactive iodoacetamido group or a less reactive choloroacetamido group, [Ru(bpy)2(5-iodoacetamido-1,10-phenanthroline)] (PF6)2 and [Ru(bpy)2(5-chloroacetamido-1,10-phenanthroline)](PF6) 2, respectively, where bpy is 2,2'-bipyridine. Ru(bpy)2(phen-IA)](PF6)2 was covalently linked to human serum albumin (HSA) and human immunoglobulin G (IgG). The photoluminescence lifetime of protein-bound probes approaches 1 microsecond under ambient conditions. In the absence of rotational motions, this probe displayed an anisotropy of 0.18 for excitation at 472 nm. Anisotropy decay data were used to determine the overall rotational correlation times of HSA and IgG. These long-lifetime sulfhydryl-reactive probes can be used to recover microsecond rotational motions and/or domain motions of proteins and/or macromolecular complexes.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA.
authors.forename: F N
authors.initials: FN
authors.lastname: Castellano
authors.forename: J D
authors.initials: JD
authors.lastname: Dattelbaum
authors.forename: J R
authors.initials: JR
authors.lastname: Lakowicz
mesh_terms: D003545:Cysteine / Q000032:analysis; D006801:Humans; D008163:Luminescent Measurements; D009942:Organometallic Compounds / Q000737:chemistry*; D011506:Proteins / Q000032:analysis*; D012428:Ruthenium / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods; D013438:Sulfhydryl Compounds / Q000032:analysis*
chemical_list: D009942:Organometallic Compounds; D011506:Proteins; D013438:Sulfhydryl Compounds; D012428:Ruthenium; D003545:Cysteine